Parathyroid hormone antagonists

ABSTRACT

Peptide derivatives of the following general formula (I): ##STR1## wherein AAA is deletion or Ser, BBB is deletion or Glu, CCC is deletion, Ile, Phe, Leu, cyclohexylalanine, D-alle or Lys substituted at the ε-position by C 6  --C 18  alkylcarbonyl group, DDD is Gly or Gln, EEE is Leu, Nle or Phe, FFF is Met, Leu or Nle, GGG is Ala, Ser Leu, Asn, Asp or Gln, HHH is Leu, Glu or Lys, III is His, Lys or Arg, JJJ is His, Lys or Arg, Xaa is Ala modified at the carboxy terminal with an amino group, provided that CCC and DDD may independently be modified at the amino terminal by C 2  --C 18  alkylcarbonyl group, and that EEE is not Leu when FFF is Met, GGG is Asn, HHH is Leu, III and JJJ are His, and the salts thereof, which exhibit a potent inhibitory activity against hPTH and are useful as a therapeutic agent for treating dysbolism associated with calcium or phosphoric acid, such as hypercalcemia, osteoporosis, hyperparathyroidism, renal osteodystrophy, and the like, and other related diseases involving PTH or PTHrP.

This application is a continuation of now abandoned application Ser. No. 07/998,150, filed Dec. 29, 1992 which is a continuation of Ser. No. 07/684,391 filed Apr. 12, 1991, now U.S. Pat. No. 5,229,489, issued Jul. 20, 1993.

The present invention relates to novel parathyroid hormone antagonists.

Parathyroid hormone (PTH) is an important hormone controlling the calcium metabolism in living bodies. Recently, analogous peptides having an activity similar to PTH, referred to as "parathyroid hormone related peptides" (PTHrP), have been discovered. Human PTHrP is a polypeptide consisting of 141 amino acids, and its PTH-like biological activities, namely elevation of blood level of calcium, acceleration of bone resorption, lowering of blood level of phosphorus, lowering of urine level of calcium, increase of urine level of cAMP, and renal activation of hydroxylase at the 1-position of vitamin D, have recently been reported [Horiuchi, et al., Science, Vol. 238, 1988; Kemp, et al., Science, Vol. 238, 1988].

It is known that PTH fragments which lack several amino acids at the amino terminal and carboxy terminal of PTH, such as PTH (3-34), PTH (7-34) or their derivatives inhibit the PTH action, and they are useful as PTH antagonists. Similar inhibitory action has also been reported on PTHrP fragments [Suva et al., Science, Vol. 237, 893 (1987); Rabbani et al., Report at the Meeting of American Bony Metabology 1988].

European Patent Publication No. 341,962 discloses, as a human humoral hypercalcemic factor (hHGF), PTH derivatives such as hPTHrP(8-34)NH₂, hPTHrP(14-34)NH₂, and the like. However, they show insufficient activity for clinical use.

As the result of extensive study for the purpose of obtaining PTHrP derivatives showing more potent PTH antagonistic activity than known PTH or PTHrP derivatives, such as [Tyr³⁴ ]-hPTH (3-34)-NH₂, hPTHrP (3-34)-NH₂ and [Leu¹¹,D-Trp¹² ]-hPTHrP(7-34)-NH₂, the present inventors have found that a certain class of PTHrP derivatives possess excellent antagonistic activity against PTH.

Thus, the present invention provides the peptide derivatives of the following general formula (I): ##STR2## wherein AAA is deletion or Ser, BBB is deletion or Glu, CCC is deletion, Ile, Phe, Leu, cyclohexylalanine, D-alle or Lys substituted at the ε-position by C₆ --C₁₈ alkylcarbonyl group, DDD is Gly or Gln, EEE is Leu, Nle or Phe, FFF is Met, Leu or Nle, GGG is Ala, Ser, Leu, Asn, Asp or Gln, HHH is Leu, Glu or Lys, III is His, Lys or Arg, JJJ is His, Lys or Arg, Xaa is Ala modified at the carboxy terminal with an amino group, provided that CCC and DDD may independently be modified at the amino terminal by C₂ --C₁₈ alkylcarbonyl group, and that EEE is not Leu when FFF is Met, GGG is Asn, HHH is Leu, III and JJJ are His, and the salts thereof.

The present invention will be explained in detail below.

The peptide derivatives of the invention are represented by the above-mentioned formula (I), i.e., SEQ ID No. 1. In the definition of the formula (I), specific examples of the C₂ --C₁₈ alkylcarbonyl group are acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl, pivaloyl, hexanoyl, 3-methylvaleryl (3-methylpentanoyl), heptanoyl, octanoyl, nonanoyl, decanoyl, lauroyl, myristoyl, palmitoyl and stearoyl, and the C₅ --C₁₈ alkylcarbonyl group includes the above-noted groups which contains from 5 to 18 carbon atoms.

As previously stated, PTH or PTHrP fragments which lack 2-13 amino acid residues at the amino terminal show antagonistic property against PTH or PTHrP. However, such antagonistic activities are generally weak for practical use. Accordingly, development of peptide compounds having more potent antagonistic activity has long been desired. For this purpose, it is a general procedure to substitute one or more amino acids of PTH or PTHrP and then examine the activity of the resultant products. However, it is very difficult to previously estimate the result of particular substitutions. In addition, substitution of plural amino acids does not always bring about additive or synergistic effect expected from the known results in each substitution. Thus, it is far more difficult to previously estimate the results of a combination of two or more substitutions.

Under such circumstances as mentioned above, the inventors of the present invention synthesized and investigated a vast amount of PTHrP derivatives and found that the above-mentioned PTHrP derivatives of the formula (I) exhibited very potent antagonistic activity.

One of the key elements of the substitution of the amino acid or acids of PTHrP was introduction of a hydrophobic substituent at the 5- and 8- positions of naturally-occurring PTHrP and also substitution of other amino acid or acids so that the increased antagonistic activity due to the just-mentioned introduction of a hydrophobic substitution may be retained or enhanced. Another key element was introduction of a strong hydrophobic substituent into the N-terminal, which was accomplished by introduction of an amino acid bearing a hydrophobic acyl group into the N-terminal. Such substitution as mentioned above appears effective for both increase of activity and stabilization of the derivatives in a living body.

Illustrative examples of the PTHrP derivatives of the present invention are those as shown hereinafter in Table 2. These derivatives can also be converted to pharmacologically acceptable salts such as hydrochloride, acetate or the like, without loss of the activity.

The abbreviations used in the present specification have the following significances. All the amino acids have the L-form, unless otherwise stated.

Asp: Aspartic acid

Thr: Threonine

Ser: Serine

Glu: Glutamic acid

Asn: Asparagine

Gln: Glutamine

Gly: Glycine

Ala: Alanine

Met: Methionine

Met(O): Methionine sulfoxide

Ile: Isoleucine

Leu: Leucine

Phe: Phenylalanine

Tyr: Tyrosine

Lys: Lysine

His: Histidine

Arg: Arginine

Cha: βCyclohexylalanine

Nle: Norleucine

aIle: Alloisoleucine

Lys(Pal): ε-palmitoyllysine

Lys (Myr): ε-Myristoyllysine

Lys(Cap): ε-Decanoyllysine

Lys(Hex): ε-Hexanoyllysine

Ac: Acetyl

Mpa: 3-Methylpentanoyl

Hex: n-Hexanoyl

Cap: n-Decanoyl

Myr: Myristoyl

Pal: Palmitoyl

Boc: t-Butyloxycarbonyl

Z: Benzyloxycarbonyl

OcHx: Cyclohexyl ester

OBzl: Benzyl ester

Bzl: Benzyl

Bom: Benzyloxymethyl

Tos: p-Toluenesulfonyl

Cl-Z: 2-Chlorobenzyloxycarbonyl

Bop Reagent: Benzotriazo-1-yl-tris(dimethylamino)-phosphonium hexafluorophosphate

The PTHrP derivatives (I) of the present invention can be prepared by repeating the condensation reaction of each protected amino acids in the order of amino acid sequence represented by the formula (I), starting from the C-terminal, in accordance with the solid phase peptide synthesis generally adopted, and then subjecting the resultant protected peptides to acid decomposition, aminolysis or known other procedures for removing the protecting groups and solid carrier used. The derivatives can also be prepared by condensing various peptide fragments according to so-called liquid phase synthetic methods. These general synthetic methods are described in detail in various literatures and text books [Izumiya, et al., "Fundamentals and Practice of Peptide Synthesis", Maruzen, 1985: Gross & Meienhofer, "The Peptides", Vol. 2, Academic Press, 1980].

Solid carriers usable for synthesizing the peptide of the present invention are those conventionally used for the peptide synthesis. Specific examples of the carriers include substituted benzyl type polystyrene resins, hydroxymethylphenylacetamide type polystyrene resins, substituted benzhydryl polystyrene resins and polyacrylamide resins capable of binding to a peptide. The condensation of amino acids can be attained in a conventional manner used for peptide synthesis, for example, dicyclohexylcarbodiimide (DCC) method, acid anhydride method, activated ester method, or a method using Bop reagent. Protecting groups used for protecting amino acids as starting materials are those already known in the peptide synthesis, which are easily removable by known means such as acid decomposition or the like. Examples of protecting groups for an amino group in the side chain are trifluoroacetyl, benzyloxycarbonyl and substituted benzyloxycarbonyl, such as (ortho- or para-)chlorobenzyloxycarbonyl, (ortho- or para-)bromobenzyloxycarbonyl or the like. Protecting groups for an α-amino group are those comparatively instable to an acid and include t-butoxycarbonyl, t-amyloxycarbonyl, p-methoxybenzyloxycarbonyl or the like. A carboxy group is protected by an ester group. Examples thereof are benzyl ester, substituted benzyl ester, alkyl ester such as cyclohexyl ester, cycloheptyl ester or the like. A guanidino group can be used without protection, or in the protected form with nitro or arylsulfonyl, such as tosyl, methoxybenzenesulfonyl, mesitylenesulfonyl or the like. Tosyl, benzyl, dinitrophenyl, benzyloxymethyl or the like may be used for protecting an imidazole. A hydroxy group of serine and threonine can be used without protection or after protection with benzyl, substituted benzyl or the like. An indole group of tryptophane is used without protection or after protection with formyl or the like.

The final deprotection and separation of the resultant peptide from the solid carrier can be conducted by the use of dry hydrogen fluoride in the presence of various scavengers. The scavengers mean those generally used for peptide synthesis and illustratively include anisole, (ortho-, meta- or para-)cresol, dimethyl sulfoxide, thiocresol, ethanedithiol, mercaptopyridine and the like.

Elongation and deprotection of the resultant peptide can be performed in accordance with FMOC method (Fields et al. Int. J. Pept. Protein Res. 35, 16, 1990). Purification of the peptide may be performed by gel filtration, ion exchange chromatography, reversed phase chromatography under high or low pressure.

Purified peptides can be converted into their salts by gel chromatography equilibrated with an aqueous acid solution.

The PTHrP derivatives (I) of the present invention may be useful as a therapeutic agent for treating dysbolism associated with calcium or phosphoric acid, such as hypercalcemia, osteoporosis, hyperparathyroidism, renal osteodystrophy, and the like, and other related diseases involving PTH or PTHrP.

The following detailed examples are presented by way of illustration of certain specific embodiments of the invention. The examples are representative only and should not be construed as limiting the present invention in any aspect.

EXAMPLE 1

Preparation of Ile-Gln-Leu-Met-His-Asp-Lys-Gly-Lys-Ser-Ile -Gln-Asp-Leu-Arg-Arg-Arg-Phe-Phe-Leu-His-His-Leu-Ile-Ala -Glu-Ile-His-Thr-Ala-NH₂ ([Ile⁵, Met⁸ ]-hPTHrP (5-34)-NH₂ ; Compound No. 15 in Table 2):

This peptide was synthesized on 1% cross-linked 4-methylbenzhydrylamine polystyrene solid phase carrier (amino group content 0.5 mmol) in accordance with the solid phase synthetic method as previously mentioned. The following amino acid derivatives were used for preparing this peptide.

Boc-Ala, Boc-Asp (OcHx), Boc-Asn, Boc-Arg (Tos), Boc-Gly, Boc-Glu (OcHx), Boc-Gln, Boc-His (Bom), Boc-Ile, Boc-Leu, Boc-Lys (Cl-Z), Boc-Met, Boc-Phe, Boc-Ser (Bzl), Boc-Thr (Bzl).

Elongation of the peptide chain was performed by repeating the procedure asshown in Table 1.

                  TABLE 1                                                          ______________________________________                                                                 Times    Period                                        Treating method         treated  (min)                                         ______________________________________                                         Deprotection                                                                   1.  Wash with CH.sub.2 Cl.sub.2                                                                            1        1.0                                       2.  Wash with 50% CF.sub.3 COOH/CH.sub.2 Cl.sub.2                                                          1        5.0                                       3.  Deprotect with 50% CF.sub.3 COOH/CH.sub.2 Cl.sub.2                                                     1        25                                        4.  Wash with CH.sub.2 Cl.sub.2                                                                            1        1.0                                       Neutralization                                                                 1.  10% diisopropylethylamine/CH.sub.2 Cl.sub.2                                                            2        2.0                                       2.  Wash with CH.sub.2 Cl.sub.2                                                                            2        5.0                                       3.  Wash with dimethylformamide                                                                            5        1.0                                       Condensation*                                                                  1.  sym-acid anhydride of tert-Butoxy-                                                                     1        30-60                                         carbonylamino acid(2 mol equiv)**/                                             dimethylformamide                                                          2.  Wash with dimethylformamide                                                                            5        1.0                                       3.  Wash with CH.sub.2 Cl.sub.2                                                                            5        1.0                                       ______________________________________                                         *Boc--Asn, Boc--Gln, Boc--Arg (Tos) and Boc--His (Bom) were subjected to        DCC/HOBt method [Mojsov et al., J. Org. Chem., 45, 555 (1980)]. Boc--Asn,      Boc--Gln, Boc--Arg (Tos), Boc--Ile, Boc--Thr (Bzl) and Boc--His (Bom) wer     subjected to condensation twice.                                               **symAcid anhydride obtained by mixing the protected amino acids with DCC       was used without isolation.                                              

Removal of the solid carrier and protecting group was performed by known HFmethod. More particularly, the protected peptide bound to polystyrene was reacted with a mixture of 10% p-cresol, 5% dimethylsulfide, and 85% dry hydrogen fluoride at 0° C. for one hour, and the reaction mixture was concentrated under reduced pressure. The residue was washed with ethylacetate and extracted with 1M acetic acid. The extract was lyophilized to give crude peptide. The crude peptide was subjected to reversed phase highperformance liquid chromatography and eluted with 0.1% trifluoroacetic acid-acetonitrile in linear gradient. After lyophilization of relevant fractions, the partially purified peptide was subjected to CM Toyopearl 650S (1.5×20 cm) in 20 mM ammonium acetate (pH 6.0) and eluted with 20 mM-1.0M ammonium acetate in linear gradient of ion concentration. The fractions containing the peptide was lyophilized, subjected to gel filtration with Sephadex G 25 (1.5×40 cm), which was equilibrated with 2% acetic acid, for conversion into the acetate and lyophilized to give the pure product.

Yield: 40.0 mg

Amino acid analysis: The peptide sample was hydrolyzed in 5.5M hydrochloricacid at 110° C. for 48 hours and subjected to the amino acid analysis. The data within the parenthesis below represent calculated values. Correction for compensating possible decomposition of amino acids during the hydrolysis was not made.

Asp: 1.97 (2), Thr: 0.93 (1), Ser: 0.80 (1), Glu: 3.11 (3), Gly: 1.02 (1), Ala: 2.10 (2), Met: 0.94 (1), Ile: 3.74 (4), Leu: 3.98 (4), Phe: 2.06 (2),Lys: 1.91 (2), His: 3.79 (4), Arg: 3.27 (3)

Optical Rotation [α_(D) ²⁵ : -57.4° (C=0.1, 1M AcOH)

The following peptides listed in Table 2 were synthesized in the same method as in Example 1.

                                      TABLE 2                                      __________________________________________________________________________                                                    Optical Rotation                Compound                                                                             AAA BBB                                                                               CCC     DDD   EEE                                                                               FFF                                                                               GGG HHH III                                                                               JJJ                                                                               [α].sub.D.sup.25 (c                                                      0.1)                            __________________________________________________________________________     1     Ser Glu                                                                               Ile     Gln   Leu                                                                               Met                                                                               Ala Leu His                                                                               His                                                                               -61.3°                   2     Ser Glu                                                                               Ile     Gln   Leu                                                                               Met                                                                               Gln Leu His                                                                               His                                                                               -56.9°                   3     Ser Glu                                                                               Ile     Gln   Leu                                                                               Met                                                                               Leu Leu His                                                                               His                                                                               -56.7°                   4     Ser Glu                                                                               Ile     Gln   Leu                                                                               Met                                                                               Ser Leu His                                                                               His                                                                               -68.5°                   5     Ser Glu                                                                               Ile     Gln   Leu                                                                               Met                                                                               Asn Glu His                                                                               His                                                                               -54.0°                   6     Ser Glu                                                                               Ile     Gln   Leu                                                                               Leu                                                                               Asp Lys His                                                                               His                                                                               -63.8°                   7     --  -- D--aIle Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -58.1°                   8     --  -- Phe     Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -52.2°                   9     --  -- Leu     Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -62.1°                   10    --  -- --      Myr--Gln                                                                             Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -46.7°                   11    --  -- Cha     Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -78.3°                   12    --  -- Ile     Gly   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -44.0°                   13    --  -- Ile     Gln   Phe                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -64.4°                   14    --  -- Ile     Gln   Nle                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -66.0°                   15    --  -- Ile     Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -57.4°                   16    --  -- Ile     Gln   Leu                                                                               Nle                                                                               Asp Lys His                                                                               His                                                                               -62.5°                   17    --  -- Ile     Gln   Leu                                                                               Met                                                                               Ala Lys His                                                                               His                                                                               -69.9°                   18    --  -- Ile     Gln   Leu                                                                               Met                                                                               Ala Leu His                                                                               His                                                                               -61.5°                   19    --  -- Ile     Gln   Leu                                                                               Met                                                                               Asp Lys Arg                                                                               His                                                                               -52.0°                   20    --  -- Ile     Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               Lys                                                                               -61.8°                   21    --  -- Ac--Ile Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -74.9°                   22    --  -- Myr--Ile                                                                               Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -44.6°                   23    --  -- Mpa--Ile                                                                               Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               His                                                                               -61.3°                   24    --  -- Cap--Ile                                                                               Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               Lys                                                                               -54.5°                   25    --  -- Ac--Lys(Myr)                                                                           Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               Lys                                                                               -47.0°                   26    --  -- Ac--Lys(Hex)                                                                           Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               Lys                                                                               -61.9°                   27    --  -- Ac--Lys(Cap)                                                                           Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               Lys                                                                               -49.5°                   28    --  -- Ac--Lys(Pal)                                                                           Gln   Leu                                                                               Met                                                                               Asp Lys His                                                                               Lys                                                                               -39.0°                   __________________________________________________________________________     a: Measured in 1 M acetic acid. "c" in the parenthesis denotes the weight       of the peptide contained. The peptide content was determined by amino aci     analysis.                                                                 

Experiment 1. Determination of PTH Antagonism

PTH antagonism of the PTHrP derivatives (I) of the present invention was determined on the basis of the output of cAMP, using cultured mouse osteoblast MC3T3-E1.

To a multiwell-culture plate of 12-well were inoculated 1×10⁵ cells/well of the cultured cells, and the plate was incubated at 37° C. under 95% air-5% CO₂ atmosphere for 3 days after addition of α-modified MEM containing 10% semi-fetal bovine serum asa medium. Then, the medium was exchanged with α-modified MEM containing 1% bovine serum albumin and the cultured cells were incubated for 6 hours. The medium was replaced by α-modified MEM containing various concentrations of the compound of the present invention, 5×10⁻⁹ M hPTH (1-34), 1% bovine serum albumin and 1 mM isobutylmethylxanthin, and the mixture was incubated for 1 hour. The medium was separated from the cells, and the medium was used as a sample for assaying cAMP. The cells were shaken with 90% n-propyl alcohol to extract cAMP according to Yamaguchi et al., J. Biol. Chem., 262, 7711-7718(1987) for preparing another sample.

Assay of cAMP was performed using a commercially available cAMP-radioimmunoassay kit. Tables 3 and 4 below show 50% inhibition (IC₅₀) of the output of cAMP due to the compound of the present invention, when the amount of cAMP produced by 5×10⁻⁹ M hPTH (1-34) is regarded as 100%. Compound numbers in the tables correspond to those in Table 2.

[Tyr³⁴ ]-hPTH (3-34)-NH₂ and hPTHrP (3-34)-NH₂, both of which are heretofore known as a PTH antagonist, were used as active controls in Table 3, while Compound No. 15 was used as a control in Table 4.

                  TABLE 3                                                          ______________________________________                                         Compound            IC.sub.50 Ratio                                            ______________________________________                                         (Tyr34)--hPTH(3-34)--NH.sub.2                                                                      1                                                          hPTHrP(3-34)--NH.sub.2                                                                             0.087                                                      Compound No. 1      0.003                                                      Compound No. 2      0.003                                                      Compound No. 8      0.026                                                      Compound No. 15     0.017                                                      ______________________________________                                    

                  TABLE 4                                                          ______________________________________                                         Compound                IC.sub.50 Ratio                                        ______________________________________                                         (Leu11,D--Trp12)--hPTHrP(7-34)--NH.sub.2                                                               3.91                                                   Compound No. 9          1.02                                                   Compound No. 10         2.24                                                   Compound No. 14         0.922                                                  Compound No. 15         1                                                      Compound No. 16         0.930                                                  Compound No. 17         1.17                                                   Compound No. 18         1.97                                                   Compound No. 19         0.934                                                  Compound No. 20         1.01                                                   Compound No. 21         0.934                                                  Compound No. 22         0.765                                                  Compound No. 25         0.343                                                  ______________________________________                                    

As shown in Table 3 above, Compound No. 1 of the present invention showed 50% inhibition at a concentration of below about 1/300of [Tyr³⁴ ]-hPTH (3-34)-NH₂ and at a concentration of about 1/29of hPTHrP (3-34)-NH₂ when MC3T3-E1 was used.

Thus, the PTHrP derivatives (I) of the present invention are useful as a therapeutic agent for treating dysbolism associated with calcium or phosphoric acid, such as hypercalcemia, osteoporosis, hyperparathyroidism,renal osteodystrophy, and the like, and other related diseases involving PTH or PTHrP.

    __________________________________________________________________________     SEQUENCE LISTING                                                               (1) GENERAL INFORMATION:                                                       (iii) NUMBER OF SEQUENCES: 18                                                  (2) INFORMATION FOR SEQ ID NO:1:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 32 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                        SerGluIleGlnLeuMe tHisAlaLeuGlyLysSerIleGlnAspLeu                              151015                                                                         ArgArgArgPhePheLeuHisHisLeuIleAlaGluIleHisThrAla                               20 2530                                                                        (2) INFORMATION FOR SEQ ID NO:2:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 32 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                        SerGluIleGlnLeuMetHisGlnLeuGlyLysSerIleGlnAsp Leu                              151015                                                                         ArgArgArgPhePheLeuHisHisLeuIleAlaGluIleHisThrAla                               202530                                                                         (2) INFORMATION FOR SEQ ID NO:3:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                        PheGlnLeuMetHisAspLysGlyLysSerIleGlnAspLeuArgArg                               15 1015                                                                        ArgPhePheLeuHisHisLeuIleAlaGluIleHisThrAla                                     202530                                                                         (2) INFORMATION FOR SEQ ID NO:4:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                     ( B) TYPE: Amino acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                        LeuGlnLeuMetHisAspLysGlyLysSerIleGlnAspLeuArgArg                               151015                                                                         ArgPhePheLeu HisHisLeuIleAlaGluIleHisThrAla                                    202530                                                                         (2) INFORMATION FOR SEQ ID NO:5:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 29 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                            (ix) FEATURE:                                                                 (A) NAME/KEY: modified-site                                                    (B) LOCATION: 1                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Myr-Gln"                                         (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                        XaaLeuMetHisAspLysGlyLysSerIleGlnAspLeuArgArg                                  1510 15                                                                        ArgPhePheLeuHisHisLeuIleAlaGluIleHisThrAla                                     2025                                                                           (2) INFORMATION FOR SEQ ID NO:6:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                        (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 3                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Nle"                                             (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                        IleGlnXaaMetHisAspLysGlyLysSerIleGlnAspLeuArgArg                               15 1015                                                                        ArgPhePheLeuHisHisLeuIleAlaGluIleHisThrAla                                     202530                                                                         (2) INFORMATION FOR SEQ ID NO:7:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                      (B) TYPE: Amino acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                        IleGlnLeuMetHisAspLysGlyLysSerIleGlnAspLeuArgArg                               151015                                                                         ArgP hePheLeuHisHisLeuIleAlaGluIleHisThrAla                                    202530                                                                         (2) INFORMATION FOR SEQ ID NO:8:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D ) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 4                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Nle"                                             (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                        IleGlnLeuXaaHisAspLysGlyLysSerIleGlnAspLeuArgArg                               15 1015                                                                        ArgPhePheLeuHisHisLeuIleAlaGluIleHisThrAla                                     202530                                                                         (2) INFORMATION FOR SEQ ID NO:9:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                      (B) TYPE: Amino acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                        IleGlnLeuMetHisAlaLysGlyLysSerIleGlnAspLeuArgArg                               151015                                                                         ArgPhePheL euHisHisLeuIleAlaGluIleHisThrAla                                    202530                                                                         (2) INFORMATION FOR SEQ ID NO:10:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                            (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:                                      IleGlnLeuMetHisAlaLeuGlyLysSerIleGlnAspLeuArgArg                               151015                                                                         ArgPhePheLeuHisHisLeuIleAlaGluIleHisThrAla                                      202530                                                                        (2) INFORMATION FOR SEQ ID NO:11:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:                                       IleGlnLeuMetHisAspLysGly LysSerIleGlnAspLeuArgArg                              151015                                                                         ArgPhePheLeuArgHisLeuIleAlaGluIleHisThrAla                                     2025 30                                                                        (2) INFORMATION FOR SEQ ID NO:12:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:                                       IleGlnLeuMetHisAspLysGlyLysSerIleGlnAspLeuArgArg                               1 51015                                                                        ArgPhePheLeuHisLysLeuIleAlaGluIleHisThrAla                                     202530                                                                         (2) INFORMATION FOR SEQ ID NO:13:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A ) LENGTH: 32 amino acids                                                    (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: unknown                                                          (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 3                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ile, Phe, Leu,                                   cyclohexylalanine, D-alle or Lys substituted at the                            epsilon-position by C6-C18 alkylcarbonyl group, which may be                   modified at the amino terminal by C2- C18 alkylcarbonyl grp."                  (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 4                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Gly or Gln, which                                may be modified at the amino terminal by C2-C18                                alkylcarbonyl group"                                                           (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 5                                                                 (C) IDENTIFICATION METHOD:                                                    (D) OTHER INFORMATION: /note="Leu, Nle or Phe,                                 provided that this amino acid is not Leu when the amino acid                   at location 6 is Met, the amino acid at location 8 is Asn,                     the amino acid at location 9 is Leu, and the amino acids at                    locations 23 and 24 are both His"                                              (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 6                                                                (C) IDENTIFICATION METHOD:                                                      (D) OTHER INFORMATION: /note="Met, Leu or Nle"                                (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 8                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala, Ser, Leu,                                   Asn, Asp or Gln"                                                               (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 9                                                                (C) IDENTIFICATION METHOD:                                                     ( D) OTHER INFORMATION: /note="Leu, Glu or Lys"                                (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 23                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys or Arg"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 24                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys, or Arg"                                (ix) FEATURE:                                                                   (A) NAME/KEY: modified-site                                                   (B) LOCATION: 32                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala modified at                                  the carboxy terminal with an amino group"                                      (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:                                       SerGluXaaXaaXaaXaaHisXaaXaaGlyLysSerIleGlnAsp                                  15 1015                                                                        LeuArgArgArgPhePheLeuXaaXaaLeuIleAlaGluIleHis                                  202530                                                                         ThrXaa                                                                         (2) INFORMATION FOR SEQ ID NO:14:                                              (i) SEQUENCE CHARACTERISTICS:                                                   (A) LENGTH: 31 amino acids                                                    (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: unknown                                                          (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 2                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ile, Phe, Leu,                                   cyclohexylalanine, D-alle or Lys substituted at the                            epsilon-position by C6-C18 alkylcarbonyl group, which may be                    modified at the amino terminal by C2- C18 alkylcarbonyl                       group"                                                                         (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 3                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Gly or Gln, which                                may be modified at the amino terminal by C2-C18                                alkylcarbonyl group"                                                           (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                     (B) LOCATION: 4                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Nle or Phe,                                 provided that this amino acid is not Leu when the amino acid                   at location 5 is Met, the amino acid at location 7 is Asn,                     the amino acid at location 8 is Leu, and the amino acids at                    locations 22 and 23 are both His"                                              (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 5                                                                 (C) IDENTIFICATION METHOD:                                                    (D) OTHER INFORMATION: /note="Met, Leu or Nle"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 7                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala, Ser, Leu,                                   Asn, Asp or Gln"                                                               (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 8                                                                 (C) IDENTIFICATION METHOD:                                                    (D) OTHER INFORMATION: /note="Leu, Glu or Lys"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 22                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys or Arg"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 23                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note=" His, Lys, or Arg"                               (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 31                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala modified at                                  the carboxy terminal with an amino group"                                      (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:                                       GluXaaXaaXaaXaaHisXaaXaaGlyLysSerIleGlnAspLeu                                  1 51015                                                                        ArgArgArgPhePheLeuXaaXaaLeuIleAlaGluIleHisThr                                  202530                                                                         Xaa                                                                            (2) INFORMATION FOR SEQ ID NO:15:                                               (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 30 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: unknown                                                          (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 1                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ile, Phe, Leu,                                   cyclohexylalanine, D-alle or Lys substituted at the                            epsilon-position by C6-C18 alkylcarbonyl group, which may be                   modified at the amino terminal by C2- C18 alkylcarbonyl                        group"                                                                         (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 2                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Gly or Gln, which                                may be modified at the amino terminal by C2-C18                                alkylcarbonyl group"                                                           (ix) FEATURE:                                                                   (A) NAME/KEY: modified-site                                                   (B) LOCATION: 3                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Nle or Phe,                                 provided that this amino acid is not Leu when the amino acid                   at location 4 is Met, the amino acid at location 6 is Asn,                     the amino acid at location 7 is Leu, and the amino acids at                    locations 21 and 22 are both His"                                              (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                     (B) LOCATION: 4                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Met, Leu or Nle"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 6                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala, Ser, Leu,                                   Asn, Asp or Gln"                                                               (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                     (B) LOCATION: 7                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Glu or Lys"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 21                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys or Arg"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 22                                                               (C) IDENTIFICATION METHOD:                                                      (D) OTHER INFORMATION: /note="His, Lys, or Arg"                               (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 30                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala modified at                                  the carboxy terminal with an amino group"                                      (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:                                       XaaXaaXaaXaaHisXaaXaaGlyLysSerIleGlnAs pLeuArg                                 151015                                                                         ArgArgPhePheLeuXaaXaaLeuIleAlaGluIleHisThrXaa                                  202530                                                                         (2) INFORMATION FOR SEQ ID NO:16:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 29 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: unknown                                                          (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 1                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Gly or Gln, which                                may be modified at the amino terminal by C2-C18                                alkylcarbonyl group"                                                           (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 2                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Nle or Phe,                                 provided that this amino acid is not Leu when the amino acid                   at location 3 is Met, the amino acid at location 5 is Asn,                     the amino acid at location 6 is Leu, and the amino acids at                     locations 20 and 21 are both His"                                             (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 3                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Met, Leu or Nle"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 5                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala, Ser, Leu,                                   Asn, Asp or Gln"                                                               (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 6                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Glu or Lys"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 20                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys or Arg"                                 (ix) FEATURE:                                                                   (A) NAME/KEY: modified-site                                                   (B) LOCATION: 21                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys, or Arg"                                (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 29                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala modified at                                  the carboxy terminal with an amino group"                                      (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:                                       XaaXaa XaaHisXaaXaaGlyLysSerIleGlnAspLeuArgArg                                 151015                                                                         ArgPhePheLeuXaaXaaLeuIleAlaGluIleHisThrXaa                                     20 25                                                                          (2) INFORMATION FOR SEQ ID NO:17:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 30 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: unknown                                                          (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 2                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Gly or Gln, which                                 may be modified at the amino terminal by C2-C18                               alkylcarbonyl group"                                                           (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 3                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Nle or Phe,                                 provided that this amino acid is not Leu when the amino acid                   at location 4 is Met, the amino acid at location 6 is Asn,                     the amino acid at location 7 is Leu, and the amino acids at                    locations 21 and 22 are both His"                                              (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 4                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Met, Leu or Nle"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 6                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala, Ser, Leu,                                   Asn, Asp or Gln"                                                               (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 7                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Glu or Lys"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 21                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys or Arg"                                  (ix) FEATURE:                                                                 (A) NAME/KEY: modified-site                                                    (B) LOCATION: 22                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys, or Arg"                                (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 30                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala modified at                                  the carboxy terminal with an amino group"                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:                                      SerXaaXaaXaaHisXaaXaaGlyLysSerIleGlnAspLeuArg                                  151015                                                                         ArgArgPhePheLeuXaaXaaLeuIleAlaGluIleHisThrXaa                                   202530                                                                        (2) INFORMATION FOR SEQ ID NO:18:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 31 amino acids                                                     (B) TYPE: Amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: unknown                                                          (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 3                                                                 (C) IDENTIFICATION METHOD:                                                    (D) OTHER INFORMATION: /note="Gly or Gln, which                                may be modified at the amino terminal by C2-C18                                alkylcarbonyl group"                                                           (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 4                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Nle or Phe,                                 provided that this amino acid is not Leu when the amino acid                    at location 5 is Met, the amino acid at location 7 is Asn,                    the amino acid at location 8 is Leu, and the amino acids at                    locations 22 and 23 are both His"                                              (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 5                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Met, Leu or Nle"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    ( B) LOCATION: 7                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Ala, Ser, Leu,                                   Asn, Asp or Gln"                                                               (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 8                                                                (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="Leu, Glu or Lys"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 22                                                                (C) IDENTIFICATION METHOD:                                                    (D) OTHER INFORMATION: /note="His, Lys or Arg"                                 (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 23                                                               (C) IDENTIFICATION METHOD:                                                     (D) OTHER INFORMATION: /note="His, Lys, or Arg"                                (ix) FEATURE:                                                                  (A) NAME/KEY: modified-site                                                    (B) LOCATION: 31                                                               (C) IDENTIFICATION METHOD:                                                      (D) OTHER INFORMATION: /note="Ala modified at                                 the carboxy terminal with an amino group"                                      (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18:                                       SerGluXaaXaaXaaHisXaaXaaGlyLysSerIleGlnAspLeu                                  151015                                                                         ArgArgArgPhePheLe uXaaXaaLeuIleAlaGluIleHisThr                                 202530                                                                         Xaa                                                                        

What is claimed is:
 1. A peptide derivative which is selected from the group consisting of the compounds having the following formulas:(1) Ser Glu Ile Gln Leu Met His Ala Leu Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 1); (2) Ser Glu Ile Gln Leu Met His Gln Leu Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 2); (3) Phe Gln Leu Met His Asp Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 3); (4) Leu Gln Leu Met His Asp Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 4); (5) Myr-Gln Leu Met His Asp Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 5); (6) Ile Gln Nle Met His Asp Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 6); (7) Ile Gln Leu Met His Asp Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 7); (8) Ile Gln Leu Nle His Asp Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 8); (9) Ile Gln Leu Met His Ala Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 9); (10) Ile Gln Leu Met His Ala Leu Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 10); (11) Ile Gln Leu Met His Asp Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu Arg His Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 11); (12) Ile Gln Leu Met His Asp Lys Gly Lys Ser Ile Gln Asp Leu Arg Arg Arg Phe Phe Leu His Lys Leu Ile Ala Glu Ile His Thr Ala-NH₂ (SEQ ID No. 12). 